Detail missing

Can someone please add the details of pacman? There is no explanation of how it works. What are the components and their interaction? And how about related dependencies and libraries? Without that basic flow-chart concept in mind, it is very difficult to understand the roll that third-party additions or frontends might play.

This would be very interesting. libfetch, libalpm, etc. manolo 15:23, 15 November 2009 (EST)

Yes, I fully support Detail missing and I will try to write the paragraph as an Introduction. I am happy that I am not alone on this, as I just had an argument here. Doru001 (talk) 15:06, 1 February 2013 (UTC)

Well, the improvement is here: Introduction. The news statement does not look right. Where are those news about the introduction of systemd and the need to copy a directory of glibc?--Doru001 (talk) 16:38, 3 February 2013 (UTC)

I have reverted these changes. There were a couple of problems with your contribution:

I appreciate your effort, but I think this contribution needs improvement before being included at the beginning of one of ArchWiki's most prominent articles. I do agree that a high-level overview like this would be helpful. I would suggest that you avoid using any actual pacman code / commands in this section to avoid duplicating content in the rest of the article. A detailed overview in plain English would be most beneficial.

== Introduction ==
Packages in ''arch repositories'' are constantly upgraded. When a package is upgraded, its old version is removed from the repository. There are no major arch releases. Each package is upgraded as new versions become available from upstream sources. The repository is always coherent. (The packages in the repository always have compatible versions.) This type of repository is called a '''rolling archive'''. Before packages are upgraded in the '''core''', '''extra''' and '''community''' repositories, they are tested in the '''testing''' repository, to ensure that the distribution is stable.
{{ic|pacman}} saves to disk a list of packages available in the repository. This list is not automatically updated (refreshed). You can refresh the list using {{ic|pacman -Sy}}. {{ic|pacman -Syy}} refreshes the list even if it appears to be up to date. ({{ic|pacman -Syy}} is a good idea when you change the repository mirror used by {{ic|pacman}}. Mirrors can be out of sync and the package list from the old mirror may not correspond to the package list of the new mirror, even though the dates of the lists may suggest that they do.)
{{ic|pacman -S ''mypackage''}} installs {{ic|''mypackage''}} and all its dependencies. If {{ic|''mypackage''}} has been upgraded since the last refresh of the package list, then the required version of {{ic|''mypackage''}} will not be found in the repository and {{ic|pacman -S ''mypackage''}} fails with a message. {{ic|''mypackage''}}'s dependencies are listed in the '''Depends On''' entry of {{ic|''mypackage''}}'s ''metainformation''. ({{ic|''mypackage''}}'s ''metainformation'' can be listed with {{ic|pacman -Si ''mypackage''}} for packages in the package list and with {{ic|pacman -Qi ''mypackage''}} for installed packages). If {{ic|''mypackage''}} or its dependencies are already installed, they are upgraded to the version in the package list. If {{ic|pacman -S ''mypackage''}} finds any conflicts (installed packages which are listed in the '''Conflicts With''' entry of the {{ic|''mypackage''}}'s ''metainformation'') then it fails with a message. {{Warning|However, {{ic|pacman -S ''mypackage''}} does not check for broken dependencies which may appear from the possible upgrade of {{ic|''mypackage''}} or one of its dependencies. It is possible that an already installed package which depends on an upgraded package is unable to function with the new version of the upgraded package. This can happen if you have refreshed your package list but you have not upgraded all installed packges and it could break your system.}}
The solution is to never run {{ic|pacman -Sy}}, which could be followed by {{ic|pacman -S ''mypackage''}}, but to always run {{ic|pacman -Syu}}, which upgrades all packages after the refresh of the package list. This ensures that when you run {{ic|pacman -S ''mypackage''}} all packages installed on the system have compatible versions.
When you run {{ic|pacman -Syu}} there is a small chance that you will have to perform corrections on your system in order to have it running as you like. Important corrections are advertised here: [[Wiki News]]. They are very rare (three in 2012). However, you may like to run {{ic|pacman -Syu}} only when you have time to perform corrections and not when you rely on your system. It is a good idea to run {{ic|pacman -Syu}} often in order to minimize the difficulty of adjustment, whenever it arises.
{{ic|pacman -R ''mypackage''}} removes {{ic|''mypackage''}}. If other packages depend on {{ic|''mypackage''}}, then it fails with a message. In order to remove them too, run {{ic|pacman -Rc ''mypackage''}}. {{Warning|You should carefully check the list of packages to be removed before you remove them. Otherwise, you may remove packages required by your system to function.}} {{ic|pacman -R ''mypackage''}} does not remove {{ic|''mypackage''}}'s dependencies which have been installed as dependencies (not explicitly, '''Install Reason''' in {{ic|''mypackage''}}'s ''metainformation'') and are not required by other packages. In order to do that, you run {{ic|pacman -Rs ''mypackage''}}. The complete command would be {{ic|pacman -Rcs ''mypackage''}}.
{{Note|{{ic|pacman}} always lists packages to be installed or removed and asks for permission before it takes action. To inhibit any action, use {{ic|-p}}.}}
As you can see, {{ic|pacman}} operates at a lower level compared to {{ic|yum}} and {{ic|apt}}. This requires more attention from you in using it, but it also empowers you with better control over your system.
For those who have used other linux distributions before, there is a helpful [[Pacman Rosetta]].

I know that I am not the first archlinux beginner user who has trouble learning how to use pacman. The forums hold a good set of discussions on this topic, even experienced users state that they did not know about the dangers of pacman -Sy; pacman -S package. In order for this situation to arise there must be a number of conditions fulfilled:

elliptic and unclear manual. the first example that comes to my mind: UPGRADE OPTIONS (APPLY TO -S AND -U) --recursive Recursively reinstall all dependencies of the targets. This forces upgrades or reinstalls of all dependencies without requiring explicit version requirements. This is most useful in combination with the --needed flag, which will induce a deep dependency upgrade without any unnecessary reinstalls. Why does this exist, when -S and -U already include it? I am missing something. Something that should have been obvious, but it is not.

elliptic and unclear pacman page. It seems that we have an agreement on this. However, I may be not the first rejected contributor.

The Introduction must repeat the content. This is the point, to provide a friendly introduction to the content. The content must elaborate on evey point explained in the introduction.

The manual and the pacman wiki, short and elliptic as they are, succeed to use inconsistent terminology for basic unexplained notions like "rolling archive" and "synchronizing repository databases". I believe that, contrary to the comment, I provide an explanation.

Last but not least, I thought that this wiki is a place for mutual cooperation and not for mutual destruction. The comments refer to easy to fix issues, and I believe that preventing access of beginners to this introduction for the before mentioned problems is an exaggerated response.

Yes, I did overuse the personal pronouns. In most cases the text improved when I changed this. However, in some cases, the text became less clear. There are two important agents in this story: the system and the user. When you take out the personal pronouns it becomes less clear who is the agent to which the text refers. When I say that the package list can be refreshed the question arises: by whom? It is vitally important for the beginner user to know immediately that only him can do that. I did my best.

Thank you for the link to news. I remembered it overnight but still I appreciate the assistance.

I completely oppose the proposition to remove all commands from the introduction. As a beginner, I know very well what I wanted to find on this page and I did not. If the commands are missing, visual memory will be unable to link the information provided in plain English to important symbols to remember and the page will become practically of no use to the newcomer. Please do not delete the paragraph again for this reason. Accept a wider based discussion with beginner users before a decision is taken. The rest of the page has many issues to present, like for example what is that -S --recursive option doing. There are at least ten such unclear options in the manual.

I am not going to start an editing war on this page. I thought that I should help beginners like me to easier enter this distribution of linux, which is based on a very effective philosophy. However, in case that I am not supported by any other user in my endeavour, you can delete everything you like. Doru001 (talk) 11:39, 4 February 2013 (UTC)

I've looked at the revised introduction, and think Doru001 is on the right path.

Some suggestions :
Use subsections to make the text more readable :
overview
databases
installing/upgrading
removing

About pacman -Sy :
Mention it only in the databases subsection with its 2 use-cases (repo added, switching mirrors).
Make clear it's only a good choice for those cases, and a bad choice for all others.
(Lone_Wolf (talk) 13:13, 4 February 2013 (UTC))

Thank you very much for your support. Your suggestions are very good (I suppose that you mean -Syy, no -Sy). I am short on time, so anybody is invited to put them into the text.

Hi, Doru001 what you suggest is very usuful. But the way you push out the changes is wrong. Your edit is a major one on one of the most important ArchWiki page. So discussion on talk page is needed. Here is my suggestion:

Since most of your info is already exist in this page and it looks like some kind of tutorials. You can create a new Classroom page such as How to use pacman.

OK, I did it. If you have suggestions then please offer to help, I am really short of time.--Doru001 (talk) 10:50, 6 February 2013 (UTC)

I don't know how to use this classroom. Please connect my Pacman - An Introduction page to this project. I understand that Classroom is melted into wiki.archlinux.org? Doru001 (talk) 11:01, 6 February 2013 (UTC)

Thanks. It looks much better now.

Pacman will be the official source of information. Everyone should read it from top to down or they will have problem s sooner or later.

Pacman - An Introduction will be an easy tutorial. It will only cover the most frequently tasks the user has to perform. [somebody else]

So you say that there are no missing details on this page. Please remember to sign your comments. Doru001 (talk) 11:20, 10 February 2013 (UTC)

Pacman refuses to delete corrupted package, because it is corrupted...

I had this issue today with two packages (icu-4.4-2-x86_64.pkg.tar.xz and ttf-bitstream-vera-1.10-7-any.pkg.tar.xz). Got asked "<X> is corrupted. Do you want to delete it? [Y/n]" and then told "failed to commit transaction - <x> is invalid or corrupted". Some nice person should add in "Troubleshooting" that in this case one can delete said package manually as root in /var/cache/pacman/pkg. -- Misc 20:17, 17 April 2010 (EDT)

I'm glad someone asked this. And thanks for the pointer. One of the most annoying things that I've found users have ever had to deal with in the last couple decades has been this sort of problem with automated package management methods, regardless of the OS used. I have noticed, however, that the download process usually weeds out the corrupted downloads before committing them to the install process. It might be that dumping a bad package might be something that is automated by the pacman routine in a better manner than it does now, but downloading again, and overwriting the bad one, should fix the problem without further effort. - KitchM 23:01, 18 April 2010 (EDT)

proposed addition to package cache cleaning...

Comment: I think people will find value if the following was added to the page. Might be good to insert it between the pacman -Sc and pacman -Scc descriptions. What do others think?

Alternatively, the [CacheClean] python script can be used to manage one's pacman cache. Functionally, the script acts like the "pacman -Sc" command with a key difference: the user can select how many old versions (generations) of his/her packages to keep. For example, the following command will keep two versions of the cached packages, deleting everything else in the /var/cache/pacman/pkg directory.